1. Field of the Invention
The present invention relates to a neutron flux mapping system and a control method for a neutron flux mapping system that, in the case where a neutron detector is used again, allow a worker to inspect each apparatus while being prevented from being exposed to radiation.
2. Description of the Background Art
In a conventional neutron flux mapping system, a neutron detector is replaced with a new neutron detector upon every periodic inspection work. Upon this replacement, a drive cable connected to the neutron detector is cut such that a slightly long portion from the tip thereof inserted into a reactor, including a portion with a high dose rate, is left in a storage tube. Then, the neutron detector with a high dose rate is stored in the storage tube. Since the rest of the drive cable is a portion that is not inserted into a reactor, the rest of the drive cable has almost no dose. Therefore, the rest of the drive cable is rolled up into a drive unit, detached by a worker with its hand, and then discarded (for example, see Patent Document 1).
Recently, the quality of a neutron detector is improved and can be used for a long period. Therefore, in a neutron flux mapping system, a neutron detector may be used again, instead of replacing the neutron detector with a new neutron detector upon every periodic inspection. In this case, the neutron detector is rolled up into a drive unit, detached by a worker with the hand, and then stored in another place.
Patent Document 1: Japanese Laid-Open Patent Publication No. 62-105085
Conventionally, a neutron detector is rolled up into a drive unit, detached by hand, and then stored in another place. Meanwhile, a path transfer device and the like are inspected. After the inspection is completed, the neutron detector with a high dose rate is returned to the drive unit. Since a neutron detector that has been used in one cycle (one cycle=a period from a periodic inspection to the next periodic inspection) has a high dose rate, there is a problem of causing risk of radiation exposure.